An ANA test is a common test done to help diagnose a small group of autoimmune disorders which includes lupus, scleroderma, Sjogren’s syndrome, and rheumatoid arthritis. ANA stands for Antinuclear Antibodies. These antibodies are proteins made by your immune system which inappropriately target the tissues of your body.
Your body has a wide range of defenses which it uses to protect itself from disease. Antibodies are proteins made by your immune system that help protect against invading bacteria and viruses. From time to time, these antibodies will malfunction and inappropriately target your tissues and organs. When this happens, these antibodies become known as autoantibodies. Autoantibodies can cause a significant amount of damage to the tissues of your skin, joints, lungs, kidneys, and many other organs.
Fortunately, doctors have developed tests which can help identify the presence of these autoantibodies. An ANA test is one of these tools which doctors used to determine the presence of autoantibodies. An ANA test is not specific to any one disease, and it does not confirm a diagnosis of any particular disorder. Instead, this test is used in combination with clinical symptoms, and other exams that a doctor does, in order to establish a specific diagnosis.
The ANA test is commonly done when a doctor suspects a patient may have lupus. Rheumatoid arthritis, scleroderma, Graves’ disease, Hashimoto’s thyroiditis, and a wide range of other autoimmune diseases can also cause a positive ANA test.
There are three major subtypes of anti-nuclear antibodies which can be detected with an ANA test. The first subtype is known to attack DNA directly. These antibodies are most commonly seen in people with rheumatoid arthritis or lupus.
The second type of antinuclear antibody attacks a substance known as chromatin. Chromatin is a complex molecule which contains both protein and DNA. Antibodies which attack chromatin are seen most commonly in people with lupus and in those with autoimmune disorders involving the kidneys.
The final subtype of antinuclear antibodies target a group of proteins known as histones. Histones are proteins which are used to support the structure of DNA.
In addition to these major subtypes of antinuclear antibodies, there are a few other types as well. For example, anti-Smith and anti-RNP antibodies are common markers used to help a doctor diagnose lupus.
It should be noted that a positive antinuclear antibody test does not necessarily mean that a person has lupus. These tests have a high rate of false positive results. It is quite possible to have a positive ANA test and be free of disease. A positive ANA test must be considered in context of the symptoms presented by the patient. A person with symptoms of lupus, and a strongly positive ANA test is likely to have the disease.
AMA tests can be quite complicated and confusing. If you have further questions about antinuclear antibody testing, be sure to make an appointment to speak with your doctor. Information found on the Internet, such as what is seen in articles like this, is rarely a good substitute for a one-on-one conversation with your doctor.